Feed unit for feeding sheets to a packing line

ABSTRACT

A feed unit for feeding sheets to a packing line, wherein a pickup device engages a withdrawal opening of a hopper, housing a stack of sheets, to withdraw one sheet from the stack and feed the sheet to the packing line; at least one supporting member is located at the withdrawal opening of the hopper to reduce the passage section of the withdrawal opening and retain the sheets in the stack inside the hopper, and is movable in an adjustment direction; and an adjusting member is connected to the supporting member to adjust, in use, the position of the supporting member in the adjustment direction as a function of the size, measured in the adjustment direction, of the sheets located close to the withdrawal opening.

The present invention relates to a feed unit for feeding sheets to a packing line.

The present invention may be used to advantage for feeding tax stamps to a packing line of an automatic machine for producing packets of cigarettes, to which the following description refers purely by way of example.

BACKGROUND OF THE INVENTION

An automatic machine for producing packets of cigarettes normally comprises a station for applying tax stamps, where a tax stamp is applied to the outer surface of each packet of cigarettes in such a position that the tax stamp must be torn for access to the cigarettes inside the packet. The tax stamp application station comprises a feed unit for supplying a succession of tax stamps by withdrawing them from the bottom of a vertical stack housed inside a hopper, or by cutting them off a continuous strip unwound off a reel.

One example of a feed unit for withdrawing single sheets from the bottom of a stack inside a hopper is described in U.S. Pat. No. 4,918,908 A1, in which a suction pickup roller is rolled along a sheet at a bottom opening of the hopper to roll up the sheet; and, once the sheet is rolled up completely, the pickup roller is stopped in a release position to release the sheet to an input conveyor defined by two pickup rollers parallel and tangent to each other to engage the sheet between them.

Another example of a feed unit for withdrawing single sheets from the bottom of a stack inside a hopper is described in Patent Application EP 970885 A1, in which a wheel, rotating about its axis, feeds a pickup head continuously along an endless path through a loading station, where the pickup head, oscillating with respect to the wheel about an axis parallel to the wheel axis, engages a withdrawal opening in the hopper to withdraw a sheet, and through a follow-up unloading station, where the pickup head, rotating together with the wheel, feeds the sheet to a conveyor roller.

Other examples of feed units for withdrawing single sheets from the bottom of a stack inside a hopper are described in U.S. Pat. No. 3,881,719 A1, Patent Application GB 1571741, and Patent Application JP 2004075260 A.

At the withdrawal opening, a hopper has supporting members for supporting the sheets inside the hopper from underneath and vertically supporting the stack to prevent the sheets from falling out by force of gravity. To extract a sheet from the hopper, a suction pickup head engages the underside surface of the sheet to pull the sheet downwards, so that the sheet curves towards the centre to release the lateral portions of the sheet from the supporting members and so slip through the withdrawal opening of the hopper.

Tax stamps have been found to have a fairly wide dimensional tolerance (as much as 1 mm over a total size of 20-25 mm), and, since the supporting members must be set to permit withdrawal of the larger stamps (upper tolerance limit), the smaller stamps (lower tolerance limit) are inadequately supported by the supporting members, and are often withdrawn from the hopper together with the stamps underneath. Multiple withdrawal of two or more tax stamps is substantially caused by poor support of the “smaller” stamps, and is further compounded by the slight gluing effect of the ink with which the stamps are printed, and by the thinness of the stamps themselves, the porosity of which permits passage of the suction generated by the suction pickup head.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a feed unit for feeding sheets to a packing line, which feed unit is designed to eliminate the aforementioned problems, while at the same time being cheap and easy to produce.

According to the present invention, there is provided a feed unit for feeding sheets to a packing line, as claimed in the attached Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic view in perspective of a feed unit for feeding sheets to a packing line, in accordance with the present invention;

FIG. 2 shows a schematic side view, with parts removed for clarity, of a hopper of the feed unit;

FIG. 3 shows a schematic section, with parts removed for clarity, along line III-III of the FIG. 2 hopper;

FIG. 4 shows a schematic section, with parts removed for clarity, along line IV-IV of the FIG. 2 hopper;

FIG. 5 shows a schematic plan view, with parts removed for clarity, of the FIG. 2 hopper;

FIG. 6 shows a view in perspective of a detail of the FIG. 2 hopper.

DETAILED DESCRIPTION OF THE INVENTION

Number 1 in FIG. 1 indicates as a whole a feed unit for feeding tax stamps 2 to a packing line (not shown) of an automatic machine for producing packets of cigarettes. More specifically, feed unit 1 feeds tax stamps 2 to a tax stamp application station located along the packing line, and which applies a tax stamp to the outer surface of each packet of cigarettes, in such a position that the tax stamp must be torn for access to the cigarettes inside the packet.

Feed unit 1 comprises a vertical hopper 3, which houses a stack 4 of tax stamps 2 extending in a vertical feed direction D1, and has a bottom withdrawal opening 5. A pickup device 6 is located at withdrawal opening 5 of hopper 3, and engages withdrawal opening 5, in use, to withdraw individual tax stamps 2 successively from stack 4 and feed tax stamps 2 to the packing line. Hopper 3 comprises four fixed L-shaped sections 7 located at the four corners of stack 4 to laterally retain stack 4.

Pickup device 6 comprises a wheel 8 rotating about a central axis 9; and at least one suction pickup head 10 fitted to wheel 8 to move cyclically along an endless path through a loading station, where pickup head 10 engages withdrawal opening 5 of hopper 3 to withdraw a tax stamp 2, and through a follow-up unloading station, where pickup head 10 feeds tax stamp 2 to the packing line.

In an alternative embodiment not shown, pickup head 10 is fitted to wheel 8 to rotate about an axis, parallel to central axis 9 of wheel 8, under the control of a cam actuating system (as described, for example, in Patent Application EP 970885 A1). Alternatively, pickup device 6 may be designed differently, e.g. as described in U.S. Pat. No. 4,918,908 A1.

As shown in FIGS. 2-5, five fixed supporting members 11 are located at withdrawal opening 5 of hopper 3, and each have one end extending inside withdrawal opening 5, perpendicularly to feed direction D1, to reduce the passage section of withdrawal opening 5 and retain tax stamps 2 in stack 4 inside hopper 3. As shown more clearly in FIG. 5, two supporting members 11 are arranged uniformly along a major lateral wall 12 of stack 4, and three supporting members 11 are located along a major lateral wall 13 of stack 4 parallel to and opposite major lateral wall 12.

Each supporting member 11 is defined by a screw screwed through a threaded through hole 14 formed through a frame 15 fitted to fixed sections 7 of hopper 3; tightening or loosening each supporting member 11 with respect to frame 15 provides for adjusting the position of supporting member 11 with respect to withdrawal opening 5. It should be pointed out that the position of supporting members 11 with respect to withdrawal opening 5 is adjusted to adapt the size of withdrawal opening 5 to the size of tax stamps 2, and can only be done during maintenance/setup, after stopping feed unit 1.

Another supporting member 16 (shown in perspective in FIG. 6) is located at withdrawal opening 5 to reduce the passage section of withdrawal opening 5 to retain tax stamps 2 in stack 4 inside hopper 3, and is mounted to move in an adjustment direction D2 perpendicular to feed direction D1. As shown more clearly in FIG. 5, supporting member 16 is located at major lateral wall 12 of stack 4, between the two supporting members 11, and is connected to an adjusting member 17 for adjusting, in use, the position of supporting member 16 in adjustment direction D2 as a function of the size, measured in adjustment direction D2, of tax stamps 2 close to withdrawal opening 5.

In the preferred embodiment shown in the attached drawings, adjusting member 17 is elastic, and pushes supporting member 16 elastically with a given force towards stack 4 in adjustment direction D2. Elastic adjusting member 17, by means of supporting member 16, also pushes in adjustment direction D2 the tax stamps 2 located close to withdrawal opening 5, so that the supporting members 11 at major lateral wall 13 of stack 4 act as a stop member for tax stamps 2, in opposition to the thrust exerted by adjusting member 17 by means of supporting member 16.

In an alternative embodiment not shown, adjusting member 17 comprises a motor (normally electric) to move supporting member 16 in adjustment direction D2; in which case, the motor may be controlled by a sensor for determining the actual size and/or arrangement of the tax stamps 2 located close to withdrawal opening 5.

The preferred embodiment shown in the drawings comprises a deformable elastic body 18, which is made of elastic spring steel and comprises a portion 19 defining supporting member 16, and an L-shaped portion 20 defining elastic adjusting member 17. Portion 19 of elastic body 18 is horizontal, i.e. perpendicular to feed direction D1, and forms with portion 20 an obtuse angle of over 90° and normally ranging between 95° and 110°.

Portion 20 of elastic body 18 is fixed rigidly in an adjustable position to fixed frame 15; for which purpose, portion 20 of elastic body 18 has an elongated slot 21, which is engaged by a screw 22 screwed into a threaded hole formed through frame 15.

The tax stamps 2 close to withdrawal opening 5 are separated by a pair of nozzles 23, each of which is connected to a compressed-air source 24 and located close to withdrawal opening 5 to blow a jet of compressed air onto stack 4 in a blow direction D3 parallel to tax stamps 2 and perpendicular to adjustment direction D2. As shown more clearly in FIG. 5, both nozzles 23 face a minor lateral wall 25 of stack 4 perpendicular to major lateral walls 12 and 13, so that blow direction D3 is perpendicular to minor lateral wall 25 of stack 4, and adjustment direction D2 is perpendicular to major lateral walls 12 and 13 of stack 4.

Additional fixed supporting members 26 (shown by dash lines in FIG. 5) may also be provided at minor lateral wall 25 of stack 4 and at a minor lateral wall 27 of stack 4 parallel to and opposite minor lateral wall 25 of stack 4.

In an alternative embodiment not shown, the retaining sections 7 of hopper 3, as opposed to being vertical, may slope with respect to the vertical, or be horizontal (i.e. feed direction D1 may not be vertical); in which latter case, feed unit 1 must comprise a push device for easing stack 4 towards withdrawal opening 5 (in the hopper 3 shown, this is done by force of gravity, which tends to pull tax stamps 2 in stack 4 downwards).

In actual use, suction pickup head 10 engages and exerts force on a tax stamp 2 to extract it from withdrawal opening 5 of the hopper through the passage defined by supporting members 11, 16 and 26. The passage being smaller than each tax stamp 2, tax stamp 2 is necessarily deformed elastically to extract it from hopper 3. Any variation, due to manufacturing tolerances, in the size of tax stamps 2 in adjustment direction D2 is compensated by instantaneous, automatic adjustment to the position of supporting member 16, thus ensuring adequate support of the smaller tax stamps 2 (lower tolerance limit) to prevent multiple withdrawal, while at the same time avoiding excessive support of the larger tax stamps 2, which would thus be difficult or impossible to withdraw.

Feed unit 1 as described above may be used to supply any kind of sheet, e.g. blanks for producing rigid packages, sheets of packing material for producing soft packages, or labels or stamps applied inside or outside a package. 

1) A feed unit for feeding sheets to a packing line; the feed unit (1) comprising: a hopper (3) having a withdrawal opening (5) and housing a stack (4) of sheets (2) extending in a feed direction (D1); and a pickup device (6), which engages the withdrawal opening (5) of the hopper (3) to withdraw a single sheet (2) from the stack (4) through the withdrawal opening (5), and feed the sheet (2) to the packing line; the feed unit (1) being characterized by comprising: at least one first supporting member (16), which is located at the withdrawal opening (5) and perpendicular to the feed direction (D1) to reduce the passage section of the withdrawal opening (5) and retain the sheets (2) in the stack (4) inside the hopper (3), and is movable in an adjustment direction (D2) perpendicular to the feed direction (D1); and an adjusting member (17) for adjusting, in use, the position of the first supporting member (16) in the adjustment direction (D2) as a function of the size, measured in the adjustment direction (D2), of the sheets (2) located close to the withdrawal opening (5). 2) A feed unit as claimed in claim 1, wherein the adjusting member (17) is elastic, and pushes the first supporting member (16) elastically with a given force towards the stack (4) in the adjustment direction (D2). 3) A feed unit as claimed in claim 2, and comprising a deformable elastic body (18), which has a first portion (19) defining the first supporting member (16), and a second portion (20) defining the elastic adjusting member (17). 4) A feed unit as claimed in claim 3, wherein the first portion (19) of the elastic body (18) is perpendicular to the feed direction (D1) and forms an angle of over 90° with the second portion (20). 5) A feed unit as claimed in claim 4, wherein the first portion (19) of the elastic body (18) forms an obtuse angle of 95° to 110° with the second portion (20). 6) A feed unit as claimed in claim 3, wherein the second portion (20) of the elastic body (18) is L-shaped. 7) A feed unit as claimed in claim 3, wherein the second portion (20) of the elastic body (18) is fixed rigidly in an adjustable position to a fixed frame (15) of the hopper (3). 8) A feed unit as claimed in claim 3, wherein the deformable elastic body (18) is made of elastic spring steel. 9) A feed unit as claimed in claim 2, wherein the elastic adjusting member (17) pushes in the adjustment direction (D2) the sheets (2) located close to the withdrawal opening (5). 10) A feed unit as claimed in claim 1, and comprising at least one nozzle (23) connected to a compressed-air source (24) and located close to the withdrawal opening (5) to blow a jet of compressed air onto the stack (4) in a blow direction (D3) parallel to the sheets (2). 11) A feed unit as claimed in claim 10, wherein the first supporting member (16) is located at a first lateral wall (12) of the stack (4), and the nozzle (23) is positioned facing a second lateral wall (25) of the stack (4) perpendicular to the first lateral wall (12). 12) A feed unit as claimed in claim 11, wherein the adjustment direction (D2) is perpendicular to the first lateral wall (12) of the stack (4), and the blow direction (D3) is perpendicular to the adjustment direction (D2) and to the second lateral wall (25) of the stack (4). 13) A feed unit as claimed in claim 1, and comprising a stop member positioned contacting a third lateral wall (13) of the stack (4) on the opposite side to the first supporting member (16). 14) A feed unit as claimed in claim 1, and comprising a number of second supporting members (11) located in a fixed position at the withdrawal opening (5) and perpendicular to the feed direction (D1) to reduce the passage section of the withdrawal opening (5) and retain the sheets (2) in the stack (4) inside the hopper (3). 15) A feed unit as claimed in claim 14, and comprising three second supporting members (11) equally spaced along the third lateral wall (13) of the stack (4); and two second supporting members (11) located along the first lateral wall (12) of the stack (4) parallel to and opposite a third lateral wall (13); a first supporting member (16) being located at the first lateral wall (12) of the stack (4) and between the two second supporting members (11). 16) A feed unit as claimed in claim 1, wherein the position of the second supporting members (11) is adjustable. 17) A feed unit as claimed in claim 1, wherein the adjusting member (17) comprises a motor to move the first supporting member (16) in the adjustment direction (D2). 18) A feed unit as claimed in claim 17, wherein the adjusting member (17) comprises a sensor, which controls the motor and determines the actual size and/or arrangement of the sheets (2) located close to the withdrawal opening (5). 19) A feed unit as claimed in claim 1, wherein the pickup device (6) comprises a wheel (8) rotating about a respective central axis (9); and at least one suction pickup head (10) fitted to the wheel (8) to move cyclically along an endless path and through a loading station, where the pickup head (10) engages the withdrawal opening (5) of the hopper (3) to withdraw a respective sheet (2), and through a follow-up unloading station, where the pickup head (10) feeds the sheet (2) to the packing line. 